Electric fields can be used to manipulate cell function in a variety of ways. One specific cell mechanism that can be affected by electric fields is calcium mobilization within a cell. Calcium signaling, an important cell function, is responsible for a variety of cellular responses and actions. The release of internally stored calcium can stimulate responses to agonists, activate growth and respiration, cause the secretion of neurotransmitters, activate transcription mechanisms, cause the release of a variety of hormones, produce muscle contractions, and initiate release of key factors in the apoptosis pathway (Berridge, M. J., Bootman, M. D., Lipp, P. (1998) Nature. 395, 645-648). This calcium mobilization also triggers the influx of calcium from the external medium into the cell as a means of further propagating calcium signals and also replenishing depleted pools of calcium. Electric fields can be used to manipulate the movement of ions, such as calcium, in order to study calcium signaling.
One application of this calcium increase is to activate platelets and cause them to aggregate in vitro and in vivo. Platelet activation/aggregation is important for preventing blood loss during traumatic injury or surgery by forming a hemostatic plug at the site of injury. At present, treatment with thrombin, known to increase intracellular calcium in human platelets, is used to control slow bleeding at sites of injury. Thrombin treatment includes the topical application of bovine or recombinant thrombin, or the use of platelet gels in which autologous platelets are treated with bovine thrombin and added to the surgical site (Brissett and Hom (2003) Curr. Opin. Otolaryngol. Head Neck Surgery 11, 245-250; Man et al., (2001) Plast. Reconstr. Surg. 107, 229-237; Saltz (2001) Plast. Reconstr. Surg. 107, 238-239; Bhanot and Alex (2002) Facial Plast. Surg. 18, 27-33). However, the use of animal products could cause allergic reactions or cause possible contamination of platelet rich plasma (PRP) with infectious agents. The use of recombinant thrombin or a peptide that mimics thrombin action could be used as an alternative to animal-derived thrombin; however, this type of treatment is expensive and could also give rise to allergic reactions.
The use of cauterizing techniques will also seal blood vessels. Surgeons in the operation room commonly use this procedure. The disadvantages of cauterization are that the tissues could be burned and vessels are sealed by coagulation. This procedure induces tissue necrosis, resulting in inflammation, pain, and scarring. There is a need for a non-thermal technique that would not involve cell death, but induce platelet aggregation specifically. Such a technique would not involve sealing blood vessels by cauterization, however it would rely on the patient's own platelets to seal the blood vessel and so prevent blood loss.
Since calcium signaling plays such an important role in so many cellular functions, there remains a need to further examine this signaling mechanism and explore ways to manipulate calcium signaling pathways for therapeutic purposes. For example, there is a need to develop methods of activating calcium-mediated cell functions, including aggregation of human platelets, for therapeutic purposes, such as wound healing. These and various other needs are addressed, at least in part, by one or more embodiments of the present invention.